Radial flow column for conveying a liquid product through an adsorber material

ABSTRACT

Described is a radial flow column for conveying a liquid product through an adsorber material, more particularly for radial flow chromatography, having a housing and, arranged therein, an inner and an outer screen, each of which surrounds a longitudinal axis of the housing and between which a radial intermediate space for receiving the adsorber material is formed. The end-face end regions of the inner and outer screen are sealed with respect to the housing in order to convey the product radially through the screens and the adsorber material. Because the radial flow column comprises ring seals for radially sealing the end-face end regions and the ring seals with corresponding sealing faces permit an axial play of the screens in the housing, production tolerances of the screens with respect to one another and in relation to the housing, and longitudinal fluctuations of the screens, can be compensated in a material-preserving manner.

The invention relates to a radial flow column according to the preambleof claim 1.

Radial flow columns of this type are used, for example, for beerstabilization by polyphenol adsorption, in the production of milk forprotein adsorption and for chromatography in biotechnology. Therespective product is conveyed essentially in a radial direction throughan adsorbent material, which is filled into an intermediate spacebounded by an inner and an outer screen. Depending on the use case, aflow direction from the outside to the inside or vice versa is possible.

The inner and outer screens respectively have end-face socket ringswhich hold a screen mesh running essentially tubular-shaped betweenthem. The socket rings are welded to the end face of the housing of theradial flow column in order to seal off the end faces of the screens sothat the product can only flow through the screen mesh. The socket ringsare then placed on the housing base on the one hand and on the otherhand are fixed to a housing cover, which is formed by at least one coverflange.

In order to be able to screw the cover flange tight from above withsufficient sealing effect under tension, the longitudinal dimensions ofthe screens must be adapted exactly to the housing. For this purpose,the inner and outer screens must also be manufactured relative to eachother with comparatively low manufacturing tolerances in thelongitudinal direction. In addition to the high manufacturing costs, thefact that the screens expand longitudinally depending on the processtemperature and can thus be damaged or, conversely, the range ofpossible process temperatures is restricted to an undesirable extent isalso problematic. It has also been proved to be disadvantageous that thenon-detachable welded connection of the screens to the cover does notpermit any visual inspection, for example, with regard to contaminationof the screen mesh. In addition, it was found that the effectivenessand/or quality of the adsorption process is undesirably impaired by anuneven distribution of the product over the screen circumference on theinput side.

There is thus a need for a radial flow column that can eliminate or atleast mitigate at least one of the above problems.

The posed problem is solved with a radial flow column according to claim1. Accordingly, this is used for conveying a liquid product through anadsorber material and, in particular, for radial flow chromatography.The radial flow column comprises a housing and, arranged therein, aninner screen and an outer screen, each of which surrounds a longitudinalaxis of the radial flow column and the housing, respectively. A radialintermediate space is formed between the inner screen and the outerscreen for receiving the adsorber material. Further, end-face endregions of the inner and outer screens are sealed to the housing toradially convey the product through the screens and adsorber material.

According to the invention, the radial flow column comprises sealingrings for radially sealing the end-face end regions, wherein the sealingrings and sealing surfaces interacting therewith in each case permit anaxial play of the screens in the housing.

On the one hand, the axial play enables compensation for manufacturingtolerances of the inner and outer screens in the longitudinal direction,both relative to each other and in relation to the housing. On the otherhand, the axial clearance enables compensation for changes in the lengthof the screens due to temperature fluctuations, for example duringproduction operation, steam sterilization or the like. In both cases,harmful material stresses due to different longitudinal dimensions ofthe installed screens can be avoided, and thus also stress-relateddamage to the inner and outer screens.

The radial flow column preferably has a substantially circularcross-section. The longitudinal axis is in particular a central axis ofthe radial flow column.

The terms “axial” and “radial” always refer to the longitudinal axis ofthe radial flow column.

The axial direction is synonymous with the longitudinal direction and ispreferably vertical when the radial flow column is ready for operation.The specifications “top” and “bottom” also refer to this.

Preferably, the inner and outer screens each have an upper and a lowersocket ring on which the sealing surfaces are formed to face radiallyoutward and/or inward. The sealing surfaces can also run parallel to thelongitudinal axis. This allows the axial play to be provided in astructurally simple manner. In addition, insertion of the screens intothe housing and/or placement of the housing cover on the screens in theaxial direction is facilitated.

Preferably, the radial flow column further comprises a centraldisplacement body projecting into the inner screen, at the upper end ofwhich a fastening flange projecting radially beyond the inner screen isformed with sealing seats for the sealing rings for sealing against theinner and outer screens. This allows the screens to be easily sealedtogether towards the top.

Preferably, the upper socket ring of the inner screen is arranged at anaxial distance from the fastening flange. This allows axial play withinthe axial distance.

Preferably, the displacement body is attached in a suspended manner to acover flange which closes off the housing towards the top. This allowsthe displacement body and the screens to be fastened with low stress bymeans of screw connections.

Preferably, threaded blind holes formed at the end face towards the topof the displacement body are screwed from the outside in a load-bearingmanner to through-holes formed on the cover flange. This enables thedisplacement body to be fastened exclusively from the outside, thusavoiding problematic connecting elements from a hygienic point of view,such as cap nuts, on the side of the displacement body facing theproduct.

Preferably, an axial gap is formed between the displacement body and thecover flange for conveying the product between at least one connectionfor an external product line centrally arranged on the cover flange andan outer radial intermediate space for the product formed between theouter screen and the housing. This allows a radial product flow betweenthe connection for the external product line and the outer radialintermediate space for the product. In this respect, both an inflow ofproduct from the external product line and an outflow of product theretoare possible. This enables a simple and radially symmetrical productfeed or product discharge via a single central connection.

Preferably, the axial gap then opens substantially in itscircumferential entirety into the outer radial intermediate space. Thisfavors a circumferentially uniform distribution of the product,especially in the case of a product inflow through the axial gap. Acircumferentially uniform product distribution optimizes the adsorptioneffect of the adsorber material.

Preferably, the housing and screens are made of stainless steel, whereinthe permitted axial play is greater than a linear expansion of thestainless steel at a temperature difference of 100° C. and, inparticular, of 150° C.

The stainless steel is, for example, a stainless steel with the materialnumber 1.4404 (316L). Stainless steels with at least equivalentproperties in terms of mechanical properties and/or corrosion resistanceare also conceivable. This means that the radial flow column is alsosuitable for comparatively large temperature differences which canoccur, for example, during steam sterilization, a CIP process or thelike.

Preferably, the inner and outer screens are each detachably connected tothe housing at their two end-face end regions. This simplifiesinspection of the screens and also enables them to be replaced, forexample in the event of changes in mesh size requirements and/or forcleaning purposes. A detachable connection is understood to mean thatthe sealing rings can be detached from the corresponding sealingsurfaces and/or sealing seats without structurally changing the sealingsurfaces and/or sealing seats and that these can be reused aftercleaning if necessary.

Preferably, the sealing rings each comprise an attachment section foraxial positive locking with associated sealing seats and a sealingsection for radial sealing of corresponding sealing surfaces. Thisensures a stable position of the sealing rings in the longitudinaldirection, for example in the event of temperature fluctuations and/orduring assembly.

Preferably, the sealing rings then have an essentially L-shaped and/orT-shaped profile. This means that at least one associated profile legthen produces the axial form fit with the sealing seats and at least oneassociated profile leg is configured as a sealing section.

Preferably, the sealing rings are made of EPDM. This enables apermanently reliable sealing effect both in terms of the requiredtemperature range and the required permanent elasticity of the sealingrings.

Preferably, the sealing rings, associated sealing seats andcorresponding sealing surfaces are liquid-tight as a whole up to aninput-side process pressure of at least 10 bar. This makes it possible,for example, to prevent product and/or cleaning liquid from migratingbehind the sealing rings, which is problematic from a hygienic point ofview, both in production operations and in cleaning processes such asCIP processes.

Preferably, the intermediate space for receiving the adsorber materialhas a volume of 0.02 to 2 m³, in particular 0.1 to 0.5 m³.

A preferred embodiment of the invention is shown by a drawing. Therein:

FIG. 1 shows a longitudinal section through the radial flow column andits view from above;

FIG. 2 shows an enlarged section A from FIG. 1 ;

FIG. 3 shows an enlarged section B of FIG. 1 ; and

FIG. 4 shows an alternative longitudinal section through the radial flowcolumn and its view from below.

As can be seen from FIG. 1 , in a preferred embodiment the radial flowcolumn 1 comprises a substantially cylindrical housing 2, in which asubstantially cylindrical inner screen 3 and a substantially cylindricalouter screen 4 are arranged concentrically around a longitudinal axis laof the radial flow column 1/the housing 2. A preferably gel-likeadsorber material 5 is filled between the inner and outer screens 3, 4in a principally known manner.

An outer radial intermediate space 6 is formed between the outer screen4 and the housing 2, and a central radial intermediate space 7 is formedbetween the inner screen 3 and the outer screen 4. In addition, there isan inner radial intermediate space 8 between the inner screen 3 and adisplacement body 9, which is arranged centrally in the housing 2 andalso surrounds the longitudinal axis 1 a, which largely limits theproduct flow to an outer partial region of the radial flow column 1 in aknown manner.

A product 10 to be processed (FIG. 2 ) flows successively through theradial intermediate spaces 6, 7, 8 either from the outside to the insideor from the inside to the outside in order to convey the product 10 inthe radial direction 11 through the adsorber material 5 and therebyprocess it. For this purpose, the product 10 is applied on the inletside, for example, under a process pressure of up to 10 bar.

The invention is essentially characterized by the fact that the innerscreen 3 and the outer screen 4 are fastened in the housing 2 such thatan axial play 13 of the screens 3, 4 defined in the axial direction 12is possible with respect to the housing 2. For clarification, the axialplay 13 is indicated schematically in FIG. 2 .

The axial play 13 is made possible by sealing rings 14 which sealend-face end regions 3 a, 3 b of the inner screen 3 and end-face endregions 4 a, 4 b of the outer screen 4 in a fluid-tight manner in theradial direction 11, respectively, with respect to associated sealingsurfaces 15, see FIGS. 2 and 3 (partial regions A and B of FIG. 1 ).

The inner screen 3 consists in a principally known manner of a first(upper) socket ring 16, a second (lower) socket ring 17 and a screenmesh 18 surrounded by the latter.

Accordingly, the outer screen 4 has a first (upper) socket ring 19, asecond (lower) socket ring 20, and a screen mesh 21 surrounded thereby.

The housing 2 comprises a cover flange 22 towards the top of the endface end and a base flange 23 towards the bottom of the end face end.

For its suspended fastening to the cover flange 22, the centraldisplacement body 9 comprises an end-face fastening flange 24. Sealingseats 25 for respectively associated sealing rings 14 are formed in thefastening flange 24. In addition, an inward-facing sealing seat 26 canbe formed on the first (upper) socket ring 19 of the outer screen 4.

As indicated for the sake of clarity only in FIG. 3 , the sealing rings14 comprise anchoring sections 14 a extending substantially in theradial direction 11 to establish an axial form fit with the respectivesealing seat 25, 26, and sealing sections 14 b extending substantiallyin the axial direction 12 to establish the required radial sealingaction with the associated sealing surfaces 15.

As shown by way of example, the sealing rings 14 can have asubstantially L-shaped cross-sectional profile. T-shaped profiles arealso conceivable, in which the central leg would then be formed as ananchoring section 14 a, or functionally corresponding profiles/sealingcross sections.

Preferably, the cover flange 22 comprises a middle piece 27 screwedtightly thereto and having a central connection 28 for an upper externalproduct line (not shown). The connection 28 may be in the form of awelded-in spigot, as shown.

As can be seen from FIG. 4 , the fastening flange 24 of the displacementbody 9 is attached to the cover flange 22, preferably in a suspendedmanner from above. For this purpose, the cover flange 22 is screwed tothreaded blind holes 30 formed in the fastening flange 24, in particularthrough through-holes provided on the central middle piece 27, by meansof screws 29. The associated connecting elements are then accessibleonly from the outside so that connecting elements which are questionablefrom a hygienic point of view, such as cap nuts or the like, on thesurfaces of the cover flange 22 and the displacement body 9 which comeinto contact with the product are dispensable.

As can further be seen in FIG. 2 , an axial gap 31 (with gap widthdefined in axial direction 12) is formed between the cover flange 22 andthe fastening flange 24 as well as the upper socket ring 19 of the outerscreen 4, through which the product 10 can flow in or out in asubstantially radial direction 11. The axial gap 31 acts as a productchannel between the central connection 28 and the outer radialintermediate space 6.

The axial gap 31 is penetrated in radial direction 11 and incircumferential direction 32 only by the screws 29 so that the product10 can flow between the connection 28 and the outer radial intermediatespace 6 circumferentially evenly distributed in radial direction 11.This is schematically indicated in the top view of FIG. 1 (below).

In particular, the axial gap 31 opens over the entire circumference intothe outer radial intermediate space 6 to allow the product 10 to bedistributed as uniformly as possible in the circumferential direction 32(if the adsorber material 5, as shown, is flowed through from theoutside to the inside). In FIGS. 1 and 2 , the product flow isschematically indicated by arrows. In principle, however, the reverseflow direction is also conceivable.

A in circumferential direction entirely continuous axial gap 31improves, in particular, the distribution of the product 10 onto theadsorber material 5 on the input side compared to conventionaldistribution systems for the product 10 with tubes extending outward ina star shape.

Annular recesses 33 are formed in the bottom flange 23 to accommodatethe lower socket rings 17, 20 of the inner and outer screens 3, 4. Theassociated seal seats 25 are then preferably formed in the lateralflanks of the recesses 33.

A corresponding annular recess 34 is formed in the fastening flange 24for the upper socket ring 16 of the inner screen 3. Sealing seats 25 arethen formed in the lateral flanks of the recess 34.

For the outer screen 4, there is preferably a sealing seat 25 on theouter circumference of the fastening flange 24 and a sealing seat 26 onthe inner circumference of the upper socket ring 19.

An axial distance 35 is provided between the upper socket ring 16 of theinner screen 3 and the annular recess 34 in the fastening flange 24,which allows the axial play 13, for example, to compensate formanufacturing tolerances and/or temperature-related changes in length ofthe inner screen 3. For the upper socket ring 19 of the outer screen 4,a corresponding axial distance is provided by the axial gap 31.

For the sake of completeness, a centrally formed connection 36 on thebottom flange 23 for a lower external product line (not shown), as wellas connections 37, which can optionally be equipped with valves 38 orblind plugs 39 to supply or discharge adsorber material 5, are shown.These components of the radial flow column 1 are known in principle, sothat their arrangement and function will not be discussed in detail.

The sealing rings 14 are preferably made of EPDM to achieve the requiredpermanent elasticity and thermal and chemical resistance of the seal.

Supporting components of the housing 2 as well as the inner screen 3,the outer screen 4 and the central displacement body 9 are preferablymade of stainless steel, for example of material group 1.4404.

The screen mesh 18, 21, for example, have a mesh size of 20 to 80 μm.The mesh size depends primarily on the particle size of the adsorbermaterial 5.

The axial play 13 is preferably dimensioned such that a length expansionof the inner and outer screens 3, 4 can be compensated for essentiallywithout stress at a temperature difference of at least 100° C. Thismakes it possible to compensate for relative changes in length of thescreens 3, 4 with respect to the housing 2 if, for example, asignificantly higher temperature prevails in the area of the innerscreen 3 during sterilization and/or cleaning than in the outer area ofthe housing 2. In addition, the assembly of the radial flow column 1 islargely uncritical with respect to the manufacturing tolerances of thescreens 3, 4 in the axial direction 12.

With the sealing rings 14, for example, process pressures of up to 10bar can be permanently tolerated. This is necessary, for example, toenable flow rates of the product 10 of about 10 to 25 m³ per hour and inparticular of 15 to 22 m³ per hour. For this purpose, the central radialintermediate space 7 preferably has a capacity of 0.02 to 2 m³ and, inparticular, of 0.1 to 0.5 m³. A corresponding volume of adsorbermaterial 5 can therefore be received.

The described radial flow column 1 also allows easy access to the innerand/or outer screen 3, 4 for maintenance purposes. For example, it ispossible to check whether at least one of the screens 3, 4 isinadmissibly contaminated and/or damaged. For this purpose, the coverflange 22 and the fastening flange 24 can be lifted off together inaxial direction 12 from the housing 2 and the screens 3, 4 afterloosening their screw connection in order to inspect and/or replace thelatter. For this purpose, the screens 3, 4 also sit with their lowersocket rings 17, 20 detachably in/on the bottom flange 23 and, incontrast, are reliably sealed by the sealing rings 14 in the insertedstate.

The sealing rings 14 thus reduce the effort required to manufacture andassemble the radial flow column 1 and also allow higher processtemperatures during production and cleaning/sterilization, as well assimplified maintenance of the radial flow column 1.

1. Radial flow column for conveying a liquid product through an adsorbermaterial, comprising a housing and, arranged therein, an inner screenand an outer screen, each of which surrounds a longitudinal axis of thehousing and between which a radial intermediate space for receiving theadsorber material is formed, wherein end-face end regions of the innerscreen and the outer screen are sealed with respect to the housing inorder to convey the liquid product radially through the screens and theadsorber material, with sealing rings for radially sealing the end-faceend regions, wherein the sealing rings and sealing surfaces interactingtherewith permit axial play of the screens in the housing.
 2. Radialflow column according to claim 1, wherein the inner and outer screenseach have an upper and a lower socket ring, on which the sealingsurfaces are formed facing radially outward and/or inward.
 3. Radialflow column according to claim 2, further comprising a centraldisplacement body projecting into an inner screen, at an upper end ofwhich a fastening flange projecting radially beyond the inner screen isformed with sealing seats for the sealing rings for sealing against theinner and outer screens.
 4. Radial flow column according to claim 3,wherein an upper socket ring of the inner screen is arranged at an axialdistance from the fastening flange.
 5. Radial flow column according toclaim 3, wherein the central displacement body is attached in asuspended manner to a cover flange which closes off the housing towardsa top.
 6. Radial flow column according to claim 5, wherein threadedblind holes formed on an end face of the displacement body are screwedfrom the outside to the cover flange in a load-bearing manner.
 7. Radialflow column according to claim 5, wherein an axial gap is formed betweenthe central displacement body and the cover flange for conveying theliquid product between at least one connection for an external productline centrally arranged on the cover flange and an outer radialintermediate space for the liquid product formed between the outerscreen and the housing.
 8. Radial flow column according to claim 7,wherein the axial gap opens substantially in its circumferentialentirety into the outer radial intermediate space.
 9. Radial flow columnaccording to claim 1, wherein the housing and the screens are made ofstainless steel and the permitted axial play is greater than alongitudinal expansion of the stainless steel at a temperaturedifference of 100° C.
 10. Radial flow column according to claim 2,wherein the inner and outer screens are each detachably connected to thehousing at their two end-face end regions.
 11. Radial flow columnaccording to claim 1, wherein the sealing rings comprise an attachmentsection for an axial form fit with associated sealing seats and asealing section for radially sealing corresponding sealing surfaces. 12.Radial flow column according to claim 1, wherein the sealing rings havea substantially L-shaped and/or T-shaped cross-sectional profile. 13.Radial flow column according to claim 1, wherein the sealing rings aremade of EPDM.
 14. Radial flow column according to claim 1, wherein thesealing rings, associated sealing seats and corresponding sealingsurfaces are liquid-tight up to an input-side process pressure of atleast 10 bar.
 15. Radial flow column according to claim 1, wherein theintermediate space for receiving the adsorber material has a volume of0.02 to 2 m³.